Skeleton of a Cretaceous mammal from Madagascar reflects long-term insularity.

The fossil record of mammaliaforms (mammals and their closest relatives) of the Mesozoic era from the southern supercontinent Gondwana is far less extensive than that from its northern counterpart, Laurasia1,2. Among Mesozoic mammaliaforms, Gondwanatheria is one of the most poorly known clades, previously represented by only a single cranium and isolated jaws and teeth1-5. As a result, the anatomy, palaeobiology and phylogenetic relationships of gondwanatherians remain unclear. Here we report the discovery of an articulated and very well-preserved skeleton of a gondwanatherian of the latest age (72.1-66 million years ago) of the Cretaceous period from Madagascar that we assign to a new genus and species, Adalatherium hui. To our knowledge, the specimen is the most complete skeleton of a Gondwanan Mesozoic mammaliaform that has been found, and includes the only postcranial material and ascending ramus of the dentary known for any gondwanatherian. A phylogenetic analysis including the new taxon recovers Gondwanatheria as the sister group to Multituberculata. The skeleton, which represents one of the largest of the Gondwanan Mesozoic mammaliaforms, is particularly notable for exhibiting many unique features in combination with features that are convergent on those of therian mammals. This uniqueness is consistent with a lineage history for A. hui of isolation on Madagascar for more than 20 million years.

Publisher Correction: Late-surviving stem mammal links the lowermost Cretaceous of North America and Gondwana.

The asterisked footnote to Extended Data Table 1 should state '*Including Thomasia and Haramiyavia'. This has been corrected online.

Late-surviving stem mammal links the lowermost Cretaceous of North America and Gondwana.

Haramiyida was a successful clade of mammaliaforms, spanning the Late Triassic period to at least the Late Jurassic period, but their fossils are scant outside Eurasia and Cretaceous records are controversial1-4. Here we report, to our knowledge, the first cranium of a large haramiyidan from the basal Cretaceous of North America. This cranium possesses an amalgam of stem mammaliaform plesiomorphies and crown mammalian apomorphies. Moreover, it shows dental traits that are diagnostic of isolated teeth of supposed multituberculate affinities from the Cretaceous of Morocco, which have been assigned to the enigmatic 'Hahnodontidae'. Exceptional preservation of this specimen also provides insights into the evolution of the ancestral mammalian brain. We demonstrate the haramiyidan affinities of Gondwanan hahnodontid teeth, removing them from multituberculates, and suggest that hahnodontid mammaliaforms had a much wider, possibly Pangaean distribution during the Jurassic-Cretaceous transition.

The First Southern Hemisphere Occurrence of the Extinct Cretaceous Sclerorhynchoid Sawfish Ptychotrygon (Chondrichthyes, Batoidea), With a Review of Ptychotrygon Taxonomy.

A new extinct sclerorhynchoid sawfish, Ptychotrygon ameghinorum sp. nov., is presented here based on abundant isolated teeth and some dermal denticles, which were recovered from the Mata Amarilla Formation, belonging to the lower Upper Cretaceous of the Santa Cruz Province in the Austral Basin of Patagonia, Argentina. This new species is the first Ptychotrygon occurrence in the southern hemisphere, which so far only has been reported from northern hemisphere deposits (Europe, North Africa, and North America). The presence of P. ameghinorum sp. nov. in these southern high-latitude deposits of Patagonia, Argentina, extends the geographic range of Ptychotrygon considerably southwards. This distribution pattern in the "middle" Cretaceous seems to correlate with the South Atlantic opening at the end of the Albian. The presence of lateral cephalic dermal denticles and the simultaneous absence of rostral denticles in the abundant fossil material support the view that Ptychotrygon did not develop such rostral structures. A reinvestigation of all known species assigned to Ptychotrygon reveals that P. ellae is a junior synonym of P. boothi, P. benningensis belongs to Texatrygon, P. rugosum belongs to Asflapristis, and P. clementsi represents an unidentifiable species (Ptychotrygon? sp.). The stratigraphic distribution demonstrates that Ptychotrygon might have originated in the Albian in south-western Europe and subsequently dispersed to obtain its widest distribution during the Cenomanian. In the Coniacian, a steep diversity decline is recognizable with a subsequent distribution shift from Europe to North America.

A derived dryolestid mammal indicates possible insular endemism in the Late Jurassic of Germany.

The Langenberg Quarry near Bad Harzburg has yielded the first Jurassic stem therian mammal of Germany, recovered from Kimmeridgian (Late Jurassic) near shore deposits of a palaeo-island within the Lower Saxony Basin of the European archipelago. The new stem therian is represented by one lower and three upper molars. Hercynodon germanicus gen. et sp. nov. is attributed to the Dryolestidae, a group of pretribosphenic crown mammals that was common in western Laurasia from the Middle Jurassic to the Early Cretaceous. The new taxon is characterised by small size, a reduced cusp pattern in the upper molars lacking a metacone, and enhancement of the shearing crests paracrista and metacrista. Phylogenetic analysis identified Hercynodon gen. nov. as sister taxon of Crusafontia from the Lower Cretaceous (Barremian) of Spain. Both taxa belong to an endemic European clade of dryolestids, including also Achyrodon and Phascolestes from the earliest Cretaceous (Berriasian) of England. Despite its greater geological age, Hercynodon gen. nov. is the most derived representative of that clade, indicated by the complete reduction of the metacone. The discrepancy between derived morphology and geological age may be explained by an increased rate of character evolution in insular isolation. Other insular phenomena have earlier been observed in vertebrates from the Langenberg Quarry, such as dwarfism in the small sauropod Europasaurus, and possible gigantism in the morganucodontan mammaliaform Storchodon and the pinheirodontid multituberculate mammal Teutonodon which grew unusually large.

First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism.

Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous and Palaeogene of the Southern Hemisphere, the Gondwanatheria constitute the most poorly known of all major mammaliaform radiations. Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium from Upper Cretaceous strata in Madagascar that we assign to a new genus and species. Phylogenetic analysis strongly supports its placement within Gondwanatheria, which are recognized as monophyletic and closely related to multituberculates, an evolutionarily successful clade of Mesozoic mammals known almost exclusively from the Northern Hemisphere. The new taxon is the largest known mammaliaform from the Mesozoic of Gondwana. Its craniofacial anatomy reveals that it was herbivorous, large-eyed and agile, with well-developed high-frequency hearing and a keen sense of smell. The cranium exhibits a mosaic of primitive and derived features, the disparity of which is extreme and probably reflective of a long evolutionary history in geographic isolation.

Oldest known multituberculate stapes suggests an asymmetric bicrural pattern as ancestral for Multituberculata.

Middle ear ossicles (malleus, incus, stapes) are known for few multituberculate taxa, and three different stapedial morphotypes have been suggested: (i) slender, columelliform and microperforate, (ii) robust and rod-like, and (iii) bicrural. Reinvestigation of Upper Jurassic (Kimmeridgian) mammalian petrosals from the Guimarota coal mine in central Portugal (Western Europe) revealed an asymmetric bicrural stapes (ABS) in the paulchoffatiid Pseudobolodon oreas The middle ear ossicles displaced inside the osseous vestibule were detected by a µCT analysis. The Kimmeridgian age of the Guimarota stapes exceeds the stapes from the Early Cretaceous (Barremian) of Asia (about 122-124 Ma) by approximately 30 Myr, and is only slightly younger than the stapes of the recently described Oxfordian euharamiyidan Arboroharamiya allinhopsoni The Guimarota stapes indicates that the stapes of Lambdopsalis, described as columelliform and microperforate (small stapedial foramen), does not represent a general condition for multituberculates. The stapes of Pseudobolodon is bicrural, the anterior crus sits centrally on the oval footplate, and the stapedial head is simple and smaller than the footplate. We hypothesize that the ABS evolved from the symmetric bicrural stapes (SBS) of non-mammaliaform cynodonts. The ABS appears to be the ancestral morphotype of the mammalian SBS, and the mammalian columelliform imperforate stapes.

Comparison of analytical tools appropriate for identification of proteinaceous additives in historical mortars.

Natural organic additives such as eggs, lard, resins, and oils have been added to mortars since ancient times, because the ancient builders knew of their positive effect on the mortar quality. The tradition of adding organic materials to mortars was commonly handed down only verbally for thousands years. However, this practice disappeared in the nineteenth century, when the usage of modern materials started. Today, one of the most recent topics in the industry of building materials is the reusing of natural organic materials and searching for the forgotten ancient recipes. The research of the old technological approaches involves currently the most advanced analytical techniques and methods. This paper is focussed on testing the possibility of identification of proteinaceous additives in historical mortars and model mortar samples containing blood, bone glue, curd, eggs and gelatine, by Fourier transform infrared (FTIR) and Raman spectroscopy, gas chromatography - mass spectrometry (GC-MS), matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS), liquid chromatography-electrospray ionisation-quadrupole-time of flight mass spectrometry (LC-ESI-Q-TOF MS) and enzyme-linked immunosorbent assay (ELISA). All these methods were applied to the mortar sample taken from the interior of the medieval (sixteenth century) castle in Namest nad Oslavou in the Czech Republic and their comparison contributed to the rough estimation of the protein additive content in the mortar. The obtained results demonstrate that only LC-ESI-Q-TOF MS, MALDI-TOF MS and ELISA have the sufficiently low detection limits that enable the reliable identification of collagens in historical mortars. Graphical abstract Proteomics analyses of historical mortars.

Comparative anatomy of neonates of the three major mammalian groups (monotremes, marsupials, placentals) and implications for the ancestral mammalian neonate morphotype.

The existing different modes of reproduction in monotremes, marsupials and placentals are the main source for our current understanding of the origin and evolution of the mammalian reproduction. The reproductive strategies and, in particular, the maturity states of the neonates differ remarkably between the three groups. Monotremes, for example, are the only extant mammals that lay eggs and incubate them for the last third of their embryonic development. In contrast, marsupials and placentals are viviparous and rely on intra-uterine development of the neonates via choriovitelline (mainly marsupials) and chorioallantoic (mainly placentals) placentae. The maturity of a newborn is closely linked to the parental care strategy once the neonate is born. The varying developmental degrees of neonates are the main focus of this study. Monotremes and marsupials produce highly altricial and nearly embryonic offspring. Placental mammals always give birth to more developed newborns with the widest range from altricial to precocial. The ability of a newborn to survive and grow in the environment it was born in depends highly on the degree of maturation of vital organs at the time of birth. Here, the anatomy of four neonates of the three major extant mammalian groups is compared. The basis for this study is histological and ultrastructural serial sections of a hatchling of Ornithorhynchus anatinus (Monotremata), and neonates of Monodelphis domestica (Marsupialia), Mesocricetus auratus (altricial Placentalia) and Macroscelides proboscideus (precocial Placentalia). Special attention was given to the developmental stages of the organs skin, lung, liver and kidney, which are considered crucial for the maintenance of vital functions. The state of the organs of newborn monotremes and marsupials are found to be able to support a minimum of vital functions outside the uterus. They are sufficient to survive, but without capacities for additional energetic challenges. The organs of the altricial placental neonate are further developed, able to support the maintenance of vital functions and short-term metabolic increase. The precocial placental newborn shows the most advanced state of organ development, to allow the maintenance of vital functions, stable thermoregulation and high energetic performance. The ancestral condition of a mammalian neonate is interpreted to be similar to the state of organ development found in the newborns of marsupials and monotremes. In comparison, the newborns of altricial and precocial placentals are derived from the ancestral state to a more mature developmental degree associated with advanced organ systems.

Drp1 guarding of the mitochondrial network is important for glucose-stimulated insulin secretion in pancreatic beta cells.

Mitochondria form a tubular network in mammalian cells, and the mitochondrial life cycle is determined by fission, fusion and autophagy. Dynamin-related protein 1 (Drp1) has a pivotal role in these processes because it alone is able to constrict mitochondria. However, the regulation and function of Drp1 have been shown to vary between cell types. Mitochondrial morphology affects mitochondrial metabolism and function. In pancreatic beta cells mitochondrial metabolism is a key component of the glucose-induced cascade of insulin secretion. The goal of the present study was to investigate the action of Drp1 in pancreatic beta cells. For this purpose Drp1 was down-regulated by means of shDrp1 in insulin-secreting INS1 cells and mouse pancreatic islets. In INS1 cells reduced Drp1 expression resulted in diminished expression of proteins regulating mitochondrial fusion, namely mitofusin 1 and 2, and optic atrophy protein 1. Diminished mitochondrial dynamics can therefore be assumed. After down-regulation of Drp1 in INS1 cells and spread mouse islets the initially homogenous mitochondrial network characterised by a moderate level of interconnections shifted towards high heterogeneity with elongated, clustered and looped mitochondria. These morphological changes were found to correlate directly with functional alterations. Mitochondrial membrane potential and ATP generation were significantly reduced in INS1 cells after Drp1down-regulation. Finally, a significant loss of glucose-stimulated insulin secretion was demonstrated in INS1 cells and mouse pancreatic islets. In conclusion, Drp1 expression is important in pancreatic beta cells to maintain the regulation of insulin secretion.

Glucose-induced dissociation of glucokinase from its regulatory protein in the nucleus of hepatocytes prior to nuclear export.

The glucose phosphorylating enzyme glucokinase regulates glucose metabolism in the liver. Glucokinase activity is modulated by a liver-specific competitive inhibitor, the glucokinase regulatory protein (GRP), which mediates sequestration of glucokinase to the nucleus at low glucose concentrations. However, the mechanism of glucokinase nuclear export is not fully understood. In this study we investigated the dynamics of glucose-dependent interaction and translocation of glucokinase and GRP in primary hepatocytes using fluorescence resonance energy transfer, selective photoconversion and fluorescence recovery after photobleaching. The formation of the glucokinase:GRP complex in the nucleus of primary hepatocytes at 5 mmol/l glucose was significantly reduced after a 2 h incubation at 20 mmol/l glucose. The GRP was predominantly localized in the nucleus, but a mobile fraction moved between the nucleus and the cytoplasm. The glucose concentration only marginally affected GRP shuttling. In contrast, the nuclear export rate of glucokinase was significantly higher at 20 than at 5 mmol/l glucose. Thus, glucose was proven to be the driving-force for nuclear export of glucokinase in hepatocytes. Using the FLII2Pglu-700mu-delta6 glucose nanosensor it could be shown that in hepatocytes the kinetics of nuclear glucose influx, metabolism or efflux were significantly faster compared to insulin-secreting cells. The rapid equilibration kinetics of glucose flux into the nucleus facilitates dissociation of the glucokinase:GRP complex and also nuclear glucose metabolism by free glucokinase enzyme. In conclusion, we could show that a rise of glucose in the nucleus of hepatocytes releases active glucokinase from the glucokinase:GRP complex and promotes the subsequent nuclear export of glucokinase.

Identification of the ubiquitin-like domain of midnolin as a new glucokinase interaction partner.

Glucokinase acts as a glucose sensor in pancreatic beta cells. Its posttranslational regulation is important but not yet fully understood. Therefore, a pancreatic islet yeast two-hybrid library was produced and searched for glucokinase-binding proteins. A protein sequence containing a full-length ubiquitin-like domain was identified to interact with glucokinase. Mammalian two-hybrid and fluorescence resonance energy transfer analyses confirmed the interaction between glucokinase and the ubiquitin-like domain in insulin-secreting MIN6 cells and revealed the highest binding affinity at low glucose. Overexpression of parkin, an ubiquitin E3 ligase exhibiting an ubiquitin-like domain with high homology to the identified, diminished insulin secretion in MIN6 cells but had only some effect on glucokinase activity. Overexpression of the elucidated ubiquitin-like domain or midnolin, containing exactly this ubiquitin-like domain, significantly reduced both intrinsic glucokinase activity and glucose-induced insulin secretion. Midnolin has been to date classified as a nucleolar protein regulating mouse development. However, we could not confirm localization of midnolin in nucleoli. Fluorescence microscopy analyses revealed localization of midnolin in nucleus and cytoplasm and co-localization with glucokinase in pancreatic beta cells. In addition we could show that midnolin gene expression in pancreatic islets is up-regulated at low glucose and that the midnolin protein is highly expressed in pancreatic beta cells and also in liver, muscle, and brain of the adult mouse and cell lines of human and rat origin. Thus, the results of our study suggest that midnolin plays a role in cellular signaling of adult tissues and regulates glucokinase enzyme activity in pancreatic beta cells.

Function of pretribosphenic and tribosphenic mammalian molars inferred from 3D animation.

Appearance of the tribosphenic molar in the Late Jurassic (160 Ma) is a crucial innovation for food processing in mammalian evolution. This molar type is characterized by a protocone, a talonid basin and a two-phased chewing cycle, all of which are apomorphic. In this functional study on the teeth of Late Jurassic Dryolestes leiriensis and the living marsupial Monodelphis domestica, we demonstrate that pretribosphenic and tribosphenic molars show fundamental differences of food reduction strategies, representing a shift in dental function during the transition of tribosphenic mammals. By using the Occlusal Fingerprint Analyser (OFA), we simulated the chewing motions of the pretribosphenic Dryolestes that represents an evolutionary precursor condition to such tribosphenic mammals as Monodelphis. Animation of chewing path and detection of collisional contacts between virtual models of teeth suggests that Dryolestes differs from the classical two-phased chewing movement of tribosphenidans, due to the narrowing of the interdental space in cervical (crown-root transition) direction, the inclination angle of the hypoflexid groove, and the unicuspid talonid. The pretribosphenic chewing cycle is equivalent to phase I of the tribosphenic chewing cycle, but the former lacks phase II of the tribosphenic chewing. The new approach can analyze the chewing cycle of the jaw by using polygonal 3D models of tooth surfaces, in a way that is complementary to the electromyography and strain gauge studies of muscle function of living animals. The technique allows alignment and scaling of isolated fossil teeth and utilizes the wear facet orientation and striation of the teeth to reconstruct the chewing path of extinct mammals.

Graphene oxide and flavonoids as potential inhibitors of the spike protein of SARS-CoV-2 variants and interaction between ligands: a parallel study of molecular docking and DFT.

Nanocarriers allow the connection between biomolecules and other structures to enhance the treatment efficacy, through the biomolecule's properties to an existing drug, or to allow a better and specific delivery. Apigenin and orientin are biomolecules with excellent therapeutic properties that are proposed in the fight against COVID-19. Besides that, graphene oxide is a nanomaterial that exhibits antiviral activity and is used as a nanocarrier of several drugs. We evaluated in this work, through molecular docking, the binding affinity between these structures to the receptor-binding domain of spike protein of two coronavirus variants, Delta and Omicron. The results indicate that all the structures exhibit affinity with the two protein targets, with binding affinity values of -11.88 to -6.65 kcal/mol for the Delta variant and values of -9.58 to -13.20 kcal/mol for the Omicron variant, which is a successful value as found in the literature as a potential inhibitor of SARS-CoV-2 infection. Also, through first-principles calculations based on Density Functional Theory, the interaction of graphene oxide with the biomolecules apigenin and orientin occurred. The results exhibit weak binding energy, which indicates that physical adsorption occurs, with better results when the biomolecule is set in parallel to the nanomaterial due to attractive π-π staking. These results are conducive to the development of a nanocarrier.

Does age matter?-Efficiency of mechanical food break down in Tupaia belangeri at different ages.

The relationship of food comminution and individual age in Tupaia belangeri is investigated. It is hypothesized that with increasing age the performance of the molar dentition decreases due to progressive tooth wear. While this relationship is well-documented for herbivores, age-related test series are largely lacking for insectivorous mammals. 15 individuals of Tupaia belangeri were fed exclusively with mealworms, and their faeces were analyzed for the number and size of chitin particles. The exoskeleton of a mealworm is resistant to digestive fluids in the gastrointestinal tract, and the size of individual chitin particles indicates the effectiveness of mechanical comminution that occurs in the oral cavity during mastication. It is hypothesized that a more precise occlusion of the dentition results in smaller particle size. Although individuals of all ages (juvenile, adult, and senile) were able to effectively process mealworms with their dentition prior to digestion, a larger area of very large chitin particles (98% quantile of all particles in senile animals as compared to in the same quantile in adults) in the feces of senile animals was detected. Even though the particle size of indigestible material is irrelevant for the digestive process, these findings either document somatic senescence in the functionality of the teeth, or alternatively a change in chewing behaviour with age.

About Alternaria toxins in cocoa and chocolate products-method development and monitoring of alternariol, alternariol monomethyl ether and tenuazonic acid.

A quick and selective analytical method was developed via LC-MS/MS for the simultaneous quantitation of alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TeA) which belong to the large group of secondary metabolites produced by fungi of the genus Alternaria. Cocoa is susceptible to a number of toxin-producing microorganisms, including Aspergillus and Penicillium species. The method relies on a single-step extraction, followed by an easy clean up, dilution of the raw extract and direct analysis. To assess whether cocoa and chocolate products can be a source of Alternaria toxins, a monitoring of cocoa and chocolate products (N = 99) as well as cocoa raw and semi-finished materials (cocoa shells, cocoa masses; N = 10) was performed. As the results, cocoa and products made from cocoa (without other ingredients) are no source of the Alternaria toxins considered here.

Analysis and occurrence of matrine in liquorice raw materials - Exclusion of its application as pesticide.

A quick and selective analytical method was developed employing LC-MS/MS for the quantitation of matrine. This is known to be a natural ingredient of Sophora ssp. and is suggested to be a potential contaminant, e.g. in herbal raw materials from liquorice or confectionery products based on liquorice. To prove that the finding of matrine in liquorice roots does not originate from an active use of pesticides, wild collection areas, as well as geographical, legal and economic aspects have been studied with the help of experienced traders and suppliers in cooperation with local liquorice producers. An LC-MS/MS method was successfully developed and applied for monitoring of raw material and semi-finished products (N = 104) and afterwards a model test was performed to show that findings of matrine in liquorice products originates from a co-harvesting of nearby growing Sophora roots during the manual collection of liquorice roots.

Fossil evidence on evolution of inner ear cochlea in Jurassic mammals.

The coiled cochlea is a key evolutionary innovation of modern therian mammals. We report that the Late Jurassic mammal Dryolestes, a relative to modern therians, has derived bony characteristics of therian-like innervation, but its uncoiled cochlear canal is less derived than the coiled cochlea of modern therians. This suggests a therian-like innervation evolved before the fully coiled cochlea in phylogeny. The embryogenesis of the cochlear nerve and ganglion in the inner ear of mice is now known to be patterned by neurogenic genes, which we hypothesize to have influenced the formation of the auditory nerve and its ganglion in Jurassic therian evolution, as shown by their osteological correlates in Dryolestes, and by the similar base-to-apex progression in morphogenesis of the ganglion in mice, and in transformation of its canal in phylogeny. The cochlear innervation in Dryolestes is the precursory condition in the curve-to-coil transformation of the cochlea in mammalian phylogeny. This provides the timing of the evolution, and where along the phylogeny the morphogenetic genes were co-opted into patterning the cochlear innervation, and the full coiling of the cochlea in modern therians.

MiD51 Is Important for Maintaining Mitochondrial Health in Pancreatic Islet and MIN6 Cells.

Background: Mitochondrial dynamics are important for glucose-stimulated insulin secretion in pancreatic beta cells. The mitochondrial elongation factor MiD51 has been proposed to act as an anchor that recruits Drp1 from the cytosol to the outer mitochondrial membrane. Whether MiD51 promotes mitochondrial fusion by inactivation of Drp1 is a controversial issue. Since both the underlying mechanism and the effects on mitochondrial function remain unknown, this study was conducted to investigate the role of MiD51 in beta cells. Methods: Overexpression and downregulation of MiD51 in mouse insulinoma 6 (MIN6) and mouse islet cells was achieved using the pcDNA expression vector and specific siRNA, respectively. Expression of genes regulating mitochondrial dynamics and autophagy was analyzed by quantitative Real-Time PCR, glucose-stimulated insulin secretion by ELISA, and cellular oxygen consumption rate by optode sensor technology. Mitochondrial membrane potential and morphology were visualized after TMRE and MitoTracker Green staining, respectively. Immunofluorescence analyses were examined by confocal microscopy. Results: MiD51 is expressed in insulin-positive mouse and human pancreatic islet and MIN6 cells. Overexpression of MiD51 resulted in mitochondrial fragmentation and cluster formation in MIN6 cells. Mitochondrial membrane potential, glucose-induced oxygen consumption rate and glucose-stimulated insulin secretion were reduced in MIN6 cells with high MiD51 expression. LC3 expression remained unchanged. Downregulation of MiD51 resulted in inhomogeneity of the mitochondrial network in MIN6 cells with hyperelongated and fragmented mitochondria. Mitochondrial membrane potential, maximal and glucose-induced oxygen consumption rate and insulin secretion were diminished in MIN6 cells with low MiD51 expression. Furthermore, reduced Mfn2 and Parkin expression was observed. Based on MiD51 overexpression and downregulation, changes in the mitochondrial network structure similar to those in MIN6 cells were also observed in mouse islet cells. Conclusion: We have demonstrated that MiD51 plays a pivotal role in regulating mitochondrial function and hence insulin secretion in MIN6 cells. We propose that this anchor protein of Drp1 is important to maintain a homogeneous mitochondrial network and to avoid morphologies such as hyperelongation and clustering which are inaccessible for degradation by autophagy. Assuming that insulin granule degradation frequently suppresses autophagy in beta cells, MiD51 could be a key element maintaining mitochondrial health.

Analysis of Activity-Dependent Energy Metabolism in Mice Reveals Regulation of Mitochondrial Fission and Fusion mRNA by Voluntary Physical Exercise in Subcutaneous Fat from Male Marathon Mice (DUhTP).

Physical inactivity is considered as one of the main causes of obesity in modern civilizations, and it has been demonstrated that resistance training programs can be used to reduce fat mass. The effects of voluntary exercise on energy metabolism are less clear in adipose tissue. Therefore, the effects of three different voluntary exercise programs on the control of energy metabolism in subcutaneous fat were tested in two different mouse lines. In a cross-over study design, male mice were kept for three or six weeks in the presence or absence of running wheels. For the experiment, mice with increased running capacity (DUhTP) were used and compared to controls (DUC). Body and organ weight, feed intake, and voluntary running wheel activity were recorded. In subcutaneous fat, gene expression of browning markers and mitochondrial energy metabolism were analyzed. Exercise increased heart weight in control mice (p < 0.05) but significantly decreased subcutaneous, epididymal, perinephric, and brown fat mass in both genetic groups (p < 0.05). Gene expression analysis revealed higher expression of browning markers and individual complex subunits present in the electron transport chain in subcutaneous fat of DUhTP mice compared to controls (DUC; p < 0.01), independent of physical activity. While in control mice, voluntary exercise had no effect on markers of mitochondrial fission or fusion, in DUhTP mice, reduced mitochondrial DNA, transcription factor Nrf1, fission- (Dnm1), and fusion-relevant transcripts (Mfn1 and 2) were observed in response to voluntary physical activity (p < 0.05). Our findings indicate that the superior running abilities in DUhTP mice, on one hand, are connected to elevated expression of genetic markers for browning and oxidative phosphorylation in subcutaneous fat. In subcutaneous fat from DUhTP but not in unselected control mice, we further demonstrate reduced expression of genes for mitochondrial fission and fusion in response to voluntary physical activity.